Methods, apparatus and systems for multi-access protocol data unit sessions

ABSTRACT

A wireless transmit/receive unit (WTRU) may establish a multi-access (MA) protocol data unit (PDU) in accordance with the examples described herein. The WTRU may establish a new packet data network (PDN) connection or identify a suitable existing PDN connection in an evolved packet core (EPC), establish a MA-PDU in a 5G core network ( 5 GC), and associate the existing PDN with the MA-PDU. The WTRU may already have a MA-PDU session established in  5 GC with both  3 GGP access leg and non- 3 GPP access leg in  5 GC, and the WTRU may replace the  3 GGP access leg in  5 GC with a suitable PDN connection in EPC. The WTRU may send a request for establishing a single-access PDU session in  5 GC via non- 3 GPP access, and a  5 GC network may upgrade a PDU session established for the WTRU to a MA-PDU with  3 GGP access leg in EPC.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of priority to U.S. ProvisionalPatent Application Ser. No. 62/975,814, filed Feb. 13, 2020, thecontents thereof being incorporated by reference as if fully set forthherein.

FIELD

Embodiments disclosed herein generally relate to wireless communicationsand, for example to methods, apparatus and systems for multi-accessprotocol data unit (PDU) sessions.

RELATED ART

Mobile communications are in continuous evolution and are already at thedoorstep of their fifth generation (5G). Certain networks can beimplemented in which user equipment (UE) may access a long termevolution (LTE) network. Certain networks can be implemented in whichuser equipment (UE) may access a 5G network.

SUMMARY

It may be desirable for a wireless transmit/receive unit (WTRU) to beable to access more than one wireless network such as accessing both anLTE network and a 5G network. Described herein are systems, methods andinstrumentalities for establishing a multi-access (MA) protocol dataunit (PDU). Such a MA-PDU may be associated with multiple accessnetworks including, for example, a 3GPP access network (e.g., 5G NR) anda non-3GPP access network (e.g., WLAN). A wireless transmit/receive unit(WTRU) that has established a MA-PDU may steer traffic towards themultiple networks and may switch or split the traffic among thesenetworks. In examples, a WTRU may identify a suitable existing packetdata network (PDN) connection in an evolved packet core (EPC), establisha MA-PDU in a 5G core network (5GC), and associate the existing PDU withthe MA-PDU. In examples, a WTRU may already have a MA-PDU sessionestablished in the 5GC with both a 3GPP access leg and a non-3GPP accessleg in the 5GC, and the WTRU may replace the 3GPP access leg in the 5GCwith a suitable PDN connection in an EPC. In examples, a WTRU may send arequest for establishing a single-access PDU session in a 5GC vianon-3GPP access, and the 5GC network may upgrade a PDU sessionestablished for the WTRU to a MA-PDU with a 3GPP access leg in an EPC.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a system diagram illustrating an example communicationssystem in which one or more disclosed embodiments may be implemented.

FIG. 1B is a system diagram illustrating an example wirelesstransmit/receive unit (WTRU) that may be used within the communicationssystem illustrated in FIG. 1A according to an embodiment.

FIG. 1C is a system diagram illustrating an example radio access network(RAN) and an example core network (CN) that may be used within thecommunications system illustrated in FIG. 1A according to an embodiment.

FIG. 1D is a system diagram illustrating a further example RAN and afurther example CN that may be used within the communications systemillustrated in FIG. 1A according to an embodiment.

FIG. 2 is a diagram illustrating a MA-PDU session.

FIG. 3 is a diagram illustrating a MA-PDU session with both a 3GPPaccess leg in an EPC and a non-3GPP access leg in a 5GC.

FIG. 4 is a diagram illustrating example operations that may beperformed to associate a PDN connection with a MA-PDU session.

FIG. 5 is a diagram illustrating example operations that may beperformed to replace the 3GPP access leg of a MA-PDU session with a PDNconnection.

FIG. 6 is a diagram illustrating example operations that may beperformed to upgrade a single-access PDU session to a MA-PDU with 3GPPaccess in an EPC.

FIG. 7 is a diagram illustrating a representative procedure that may beimplemented by a WTRU to replace a 3GGP access leg of a MA-PDU sessionwith a PDN connection.

FIG. 8 is a diagram illustrating a representative procedure that may beimplemented by a WTRU to associate a PDN connection with a MA-PDUsession.

FIG. 9 is a diagram illustrating a representative procedure that may beimplemented by a WTRU to upgrade a single-access PDU session to a MA-PDUsession with a 3GPP access leg in an EPC.

FIG. 10 is a diagram illustrating a representative procedure that may beimplemented by a network entity (NE) to replace a 3GPP access leg of aMA-PDU session with a PDN connection.

FIG. 11 is a diagram illustrating a representative procedure that may beimplemented by a NE to associate a PDN connection with a MA-PDU session.

FIG. 12 is a diagram illustrating a representative procedure that may beimplemented by a NE to upgrade a single-access PDU session to a MA-PDUsession with a 3GGP access leg in an EPC.

DETAILED DESCRIPTION

FIG. 1A is a diagram illustrating an example communications system 100in which one or more disclosed embodiments may be implemented. Thecommunications system 100 may be a multiple access system that providescontent, such as voice, data, video, messaging, broadcast, etc., tomultiple wireless users. The communications system 100 may enablemultiple wireless users to access such content through the sharing ofsystem resources, including wireless bandwidth. For example, thecommunications systems 100 may employ one or more channel accessmethods, such as code division multiple access (CDMA), time divisionmultiple access (TDMA), frequency division multiple access (FDMA),orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), zero-tailunique-word DFT-Spread OFDM (ZT UW DTS-s OFDM), unique word OFDM(UW-OFDM), resource block-filtered OFDM, filter bank multicarrier(FBMC), and the like.

As shown in FIG. 1A, the communications system 100 may include wirelesstransmit/receive units (WTRUs) 102 a, 102 b, 102 c, 102 d, a RAN104/113, a CN 106/115, a public switched telephone network (PSTN) 108,the Internet 110, and other networks 112, though it will be appreciatedthat the disclosed embodiments contemplate any number of WTRUs, basestations, networks, and/or network elements. Each of the WTRUs 102 a,102 b, 102 c, 102 d may be any type of device configured to operateand/or communicate in a wireless environment. By way of example, theWTRUs 102 a, 102 b, 102 c, 102 d, any of which may be referred to as a“station” and/or a “STA”, may be configured to transmit and/or receivewireless signals and may include a user equipment (UE), a mobilestation, a fixed or mobile subscriber unit, a subscription-based unit, apager, a cellular telephone, a personal digital assistant (PDA), asmartphone, a laptop, a netbook, a personal computer, a wireless sensor,a hotspot or Mi-Fi device, an Internet of Things (IoT) device, a watchor other wearable, a head-mounted display (HMD), a vehicle, a drone, amedical device and applications (e.g., remote surgery), an industrialdevice and applications (e.g., a robot and/or other wireless devicesoperating in an industrial and/or an automated processing chaincontexts), a consumer electronics device, a device operating oncommercial and/or industrial wireless networks, and the like. Any of theWTRUs 102 a, 102 b, 102 c and 102 d may be interchangeably referred toas a UE.

The communications systems 100 may also include a base station 114 aand/or a base station 114 b . Each of the base stations 114 a , 114 bmay be any type of device configured to wirelessly interface with atleast one of the WTRUs 102 a, 102 b, 102 c, 102 d to facilitate accessto one or more communication networks, such as the CN 106/115, theInternet 110, and/or the other networks 112. By way of example, the basestations 114 a , 114 b may be a base transceiver station (BTS), aNode-B, an eNode B, a Home Node B, a Home eNode B, a gNB, a NR NodeB, asite controller, an access point (AP), a wireless router, and the like.While the base stations 114 a , 114 b are each depicted as a singleelement, it will be appreciated that the base stations 114 a , 114 b mayinclude any number of interconnected base stations and/or networkelements.

The base station 114 a may be part of the RAN 104/113, which may alsoinclude other base stations and/or network elements (not shown), such asa base station controller (BSC), a radio network controller (RNC), relaynodes, etc. The base station 114 a and/or the base station 114 b may beconfigured to transmit and/or receive wireless signals on one or morecarrier frequencies, which may be referred to as a cell (not shown).These frequencies may be in licensed spectrum, unlicensed spectrum, or acombination of licensed and unlicensed spectrum. A cell may providecoverage for a wireless service to a specific geographical area that maybe relatively fixed or that may change over time. The cell may furtherbe divided into cell sectors. For example, the cell associated with thebase station 114 a may be divided into three sectors. Thus, in oneembodiment, the base station 114 a may include three transceivers, i.e.,one for each sector of the cell. In an embodiment, the base station 114a may employ multiple-input multiple output (MIMO) technology and mayutilize multiple transceivers for each sector of the cell. For example,beamforming may be used to transmit and/or receive signals in desiredspatial directions.

The base stations 114 a, 114 b may communicate with one or more of theWTRUs 102 a, 102 b, 102 c, 102 d over an air interface 116, which may beany suitable wireless communication link (e.g., radio frequency (RF),microwave, centimeter wave, micrometer wave, infrared (IR), ultraviolet(UV), visible light, etc.). The air interface 116 may be establishedusing any suitable radio access technology (RAT).

More specifically, as noted above, the communications system 100 may bea multiple access system and may employ one or more channel accessschemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. Forexample, the base station 114 a in the RAN 104/113 and the WTRUs 102 a,102 b, 102 c may implement a radio technology such as Universal MobileTelecommunications System (UMTS) Terrestrial Radio Access (UTRA), whichmay establish the air interface 115/116/117 using wideband CDMA (WCDMA).WCDMA may include communication protocols such as High-Speed PacketAccess (HSPA) and/or Evolved HSPA (HSPA+). HSPA may include High-SpeedDownlink (DL) Packet Access (HSDPA) and/or High-Speed UL Packet Access(HSUPA).

In an embodiment, the base station 114 a and the WTRUs 102 a, 102 b, 102c may implement a radio technology such as Evolved UMTS TerrestrialRadio Access (E-UTRA), which may establish the air interface 116 usingLong Term Evolution (LTE) and/or LTE-Advanced (LTE-A) and/orLTE-Advanced Pro (LTE-A Pro).

In an embodiment, the base station 114 a and the WTRUs 102 a, 102 b, 102c may implement a radio technology such as NR Radio Access , which mayestablish the air interface 116 using New Radio (NR).

In an embodiment, the base station 114 a and the WTRUs 102 a, 102 b, 102c may implement multiple radio access technologies. For example, thebase station 114 a and the WTRUs 102 a, 102 b, 102 c may implement LTEradio access and NR radio access together, for instance using dualconnectivity (DC) principles. Thus, the air interface utilized by WTRUs102 a, 102 b, 102 c may be characterized by multiple types of radioaccess technologies and/or transmissions sent to/from multiple types ofbase stations (e.g., a eNB and a gNB).

In other embodiments, the base station 114 a and the WTRUs 102 a, 102 b,102 c may implement radio technologies such as IEEE 802.11 (i.e.,Wireless Fidelity (WiFi), IEEE 802.16 (i.e., Worldwide Interoperabilityfor Microwave Access (WiMAX)), CDMA2000, CDMA2000 1X, CDMA2000 EV-DO,Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), InterimStandard 856 (IS-856), Global System for Mobile communications (GSM),Enhanced Data rates for GSM Evolution (EDGE), GSM EDGE (GERAN), and thelike.

The base station 114 b in FIG. 1A may be a wireless router, Home Node B,Home eNode B, or access point, for example, and may utilize any suitableRAT for facilitating wireless connectivity in a localized area, such asa place of business, a home, a vehicle, a campus, an industrialfacility, an air corridor (e.g., for use by drones), a roadway, and thelike. In one embodiment, the base station 114 b and the WTRUs 102 c, 102d may implement a radio technology such as IEEE 802.11 to establish awireless local area network (WLAN). In an embodiment, the base station114 b and the WTRUs 102 c, 102 d may implement a radio technology suchas IEEE 802.15 to establish a wireless personal area network (WPAN). Inyet another embodiment, the base station 114 b and the WTRUs 102 c, 102d may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE,LTE-A, LTE-A Pro, NR etc.) to establish a picocell or femtocell. Asshown in FIG. 1A, the base station 114 b may have a direct connection tothe Internet 110. Thus, the base station 114 b may not be required toaccess the Internet 110 via the CN 106/115.

The RAN 104/113 may be in communication with the CN 106/115, which maybe any type of network configured to provide voice, data, applications,and/or voice over internet protocol (VoIP) services to one or more ofthe WTRUs 102 a, 102 b, 102 c, 102 d. The data may have varying qualityof service (QoS) requirements, such as differing throughputrequirements, latency requirements, error tolerance requirements,reliability requirements, data throughput requirements, mobilityrequirements, and the like. The CN 106/115 may provide call control,billing services, mobile location-based services, pre-paid calling,Internet connectivity, video distribution, etc., and/or performhigh-level security functions, such as user authentication. Although notshown in FIG. 1A, it will be appreciated that the RAN 104/113 and/or theCN 106/115 may be in direct or indirect communication with other RANsthat employ the same RAT as the RAN 104/113 or a different RAT. Forexample, in addition to being connected to the RAN 104/113, which may beutilizing a NR radio technology, the CN 106/115 may also be incommunication with another RAN (not shown) employing a GSM, UMTS, CDMA2000, WiMAX, E-UTRA, or WiFi radio technology.

The CN 106/115 may also serve as a gateway for the WTRUs 102 a, 102 b,102 c, 102 d to access the PSTN 108, the Internet 110, and/or the othernetworks 112. The PSTN 108 may include circuit-switched telephonenetworks that provide plain old telephone service (POTS). The Internet110 may include a global system of interconnected computer networks anddevices that use common communication protocols, such as thetransmission control protocol (TCP), user datagram protocol (UDP) and/orthe internet protocol (IP) in the TCP/IP internet protocol suite. Thenetworks 112 may include wired and/or wireless communications networksowned and/or operated by other service providers. For example, thenetworks 112 may include another CN connected to one or more RANs, whichmay employ the same RAT as the RAN 104/113 or a different RAT.

Some or all of the WTRUs 102 a, 102 b, 102 c, 102 d in thecommunications system 100 may include multi-mode capabilities (e.g., theWTRUs 102 a, 102 b, 102 c, 102 d may include multiple transceivers forcommunicating with different wireless networks over different wirelesslinks). For example, the WTRU 102 c shown in FIG. 1A may be configuredto communicate with the base station 114 a , which may employ acellular-based radio technology, and with the base station 114 b , whichmay employ an IEEE 802 radio technology.

FIG. 1B is a system diagram illustrating an example WTRU 102. As shownin FIG. 1B, the WTRU 102 may include a processor 118, a transceiver 120,a transmit/receive element 122, a speaker/microphone 124, a keypad 126,a display/touchpad 128, non-removable memory 130, removable memory 132,a power source 134, a global positioning system (GPS) chipset 136,and/or other peripherals 138, among others. It will be appreciated thatthe WTRU 102 may include any sub-combination of the foregoing elementswhile remaining consistent with an embodiment.

The processor 118 may be a general purpose processor, a special purposeprocessor, a conventional processor, a digital signal processor (DSP), aplurality of microprocessors, one or more microprocessors in associationwith a DSP core, a controller, a microcontroller, Application SpecificIntegrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs)circuits, any other type of integrated circuit (IC), a state machine,and the like. The processor 118 may perform signal coding, dataprocessing, power control, input/output processing, and/or any otherfunctionality that enables the WTRU 102 to operate in a wirelessenvironment. The processor 118 may be coupled to the transceiver 120,which may be coupled to the transmit/receive element 122. While FIG. 1Bdepicts the processor 118 and the transceiver 120 as separatecomponents, it will be appreciated that the processor 118 and thetransceiver 120 may be integrated together in an electronic package orchip.

The transmit/receive element 122 may be configured to transmit signalsto, or receive signals from, a base station (e.g., the base station 114a) over the air interface 116. For example, in one embodiment, thetransmit/receive element 122 may be an antenna configured to transmitand/or receive RF signals. In an embodiment, the transmit/receiveelement 122 may be an emitter/detector configured to transmit and/orreceive IR, UV, or visible light signals, for example. In yet anotherembodiment, the transmit/receive element 122 may be configured totransmit and/or receive both RF and light signals. It will beappreciated that the transmit/receive element 122 may be configured totransmit and/or receive any combination of wireless signals.

Although the transmit/receive element 122 is depicted in FIG. 1B as asingle element, the WTRU 102 may include any number of transmit/receiveelements 122. More specifically, the WTRU 102 may employ MIMOtechnology. Thus, in one embodiment, the WTRU 102 may include two ormore transmit/receive elements 122 (e.g., multiple antennas) fortransmitting and receiving wireless signals over the air interface 116.

The transceiver 120 may be configured to modulate the signals that areto be transmitted by the transmit/receive element 122 and to demodulatethe signals that are received by the transmit/receive element 122. Asnoted above, the WTRU 102 may have multi-mode capabilities. Thus, thetransceiver 120 may include multiple transceivers for enabling the WTRU102 to communicate via multiple RATs, such as NR and IEEE 802.11, forexample.

The processor 118 of the WTRU 102 may be coupled to, and may receiveuser input data from, the speaker/microphone 124, the keypad 126, and/orthe display/touchpad 128 (e.g., a liquid crystal display (LCD) displayunit or organic light-emitting diode (OLED) display unit). The processor118 may also output user data to the speaker/microphone 124, the keypad126, and/or the display/touchpad 128. In addition, the processor 118 mayaccess information from, and store data in, any type of suitable memory,such as the non-removable memory 130 and/or the removable memory 132.The non-removable memory 130 may include random-access memory (RAM),read-only memory (ROM), a hard disk, or any other type of memory storagedevice. The removable memory 132 may include a subscriber identitymodule (SIM) card, a memory stick, a secure digital (SD) memory card,and the like. In other embodiments, the processor 118 may accessinformation from, and store data in, memory that is not physicallylocated on the WTRU 102, such as on a server or a home computer (notshown).

The processor 118 may receive power from the power source 134, and maybe configured to distribute and/or control the power to the othercomponents in the WTRU 102. The power source 134 may be any suitabledevice for powering the WTRU 102. For example, the power source 134 mayinclude one or more dry cell batteries (e.g., nickel-cadmium (NiCd),nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion),etc.), solar cells, fuel cells, and the like.

The processor 118 may also be coupled to the GPS chipset 136, which maybe configured to provide location information (e.g., longitude andlatitude) regarding the current location of the WTRU 102. In additionto, or in lieu of, the information from the GPS chipset 136, the WTRU102 may receive location information over the air interface 116 from abase station (e.g., base stations 114 a , 114 b ) and/or determine itslocation based on the timing of the signals being received from two ormore nearby base stations. It will be appreciated that the WTRU 102 mayacquire location information by way of any suitablelocation-determination method while remaining consistent with anembodiment.

The processor 118 may further be coupled to other peripherals 138, whichmay include one or more software and/or hardware modules that provideadditional features, functionality and/or wired or wirelessconnectivity. For example, the peripherals 138 may include anaccelerometer, an e-compass, a satellite transceiver, a digital camera(for photographs and/or video), a universal serial bus (USB) port, avibration device, a television transceiver, a hands free headset, aBluetooth® module, a frequency modulated (FM) radio unit, a digitalmusic player, a media player, a video game player module, an Internetbrowser, a Virtual Reality and/or Augmented Reality (VR/AR) device, anactivity tracker, and the like. The peripherals 138 may include one ormore sensors, the sensors may be one or more of a gyroscope, anaccelerometer, a hall effect sensor, a magnetometer, an orientationsensor, a proximity sensor, a temperature sensor, a time sensor; ageolocation sensor; an altimeter, a light sensor, a touch sensor, amagnetometer, a barometer, a gesture sensor, a biometric sensor, and/ora humidity sensor.

The WTRU 102 may include a full duplex radio for which transmission andreception of some or all of the signals (e.g., associated withparticular subframes for both the UL (e.g., for transmission) anddownlink (e.g., for reception) may be concurrent and/or simultaneous.The full duplex radio may include an interference management unit toreduce and or substantially eliminate self-interference via eitherhardware (e.g., a choke) or signal processing via a processor (e.g., aseparate processor (not shown) or via processor 118). In an embodiment,the WRTU 102 may include a half-duplex radio for which transmission andreception of some or all of the signals (e.g., associated withparticular subframes for either the UL (e.g., for transmission) or thedownlink (e.g., for reception)).

FIG. 1C is a system diagram illustrating the RAN 104 and the CN 106according to an embodiment. As noted above, the RAN 104 may employ anE-UTRA radio technology to communicate with the WTRUs 102 a, 102 b, 102c over the air interface 116. The RAN 104 may also be in communicationwith the CN 106.

The RAN 104 may include eNode-Bs 160 a, 160 b, 160 c, though it will beappreciated that the RAN 104 may include any number of eNode-Bs whileremaining consistent with an embodiment. The eNode-Bs 160 a, 160 b, 160c may each include one or more transceivers for communicating with theWTRUs 102 a, 102 b, 102 c over the air interface 116. In one embodiment,the eNode-Bs 160 a, 160 b, 160 c may implement MIMO technology. Thus,the eNode-B 160 a, for example, may use multiple antennas to transmitwireless signals to, and/or receive wireless signals from, the WTRU 102a.

Each of the eNode-Bs 160 a, 160 b, 160 c may be associated with aparticular cell (not shown) and may be configured to handle radioresource management decisions, handover decisions, scheduling of usersin the UL and/or DL, and the like. As shown in FIG. 1C, the eNode-Bs 160a, 160 b, 160 c may communicate with one another over an X2 interface.

The CN 106 shown in FIG. 1C may include a mobility management entity(MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN)gateway (or PGW) 166. While each of the foregoing elements are depictedas part of the CN 106, it will be appreciated that any of these elementsmay be owned and/or operated by an entity other than the CN operator.

The MME 162 may be connected to each of the eNode-Bs 162 a, 162 b, 162 cin the RAN 104 via an S1 interface and may serve as a control node. Forexample, the MME 162 may be responsible for authenticating users of theWTRUs 102 a, 102 b, 102 c, bearer activation/deactivation, selecting aparticular serving gateway during an initial attach of the WTRUs 102 a,102 b, 102 c, and the like. The MME 162 may provide a control planefunction for switching between the RAN 104 and other RANs (not shown)that employ other radio technologies, such as GSM and/or WCDMA.

The SGW 164 may be connected to each of the eNode Bs 160 a, 160 b, 160 cin the RAN 104 via the S1 interface. The SGW 164 may generally route andforward user data packets to/from the WTRUs 102 a, 102 b, 102 c. The SGW164 may perform other functions, such as anchoring user planes duringinter-eNode B handovers, triggering paging when DL data is available forthe WTRUs 102 a, 102 b, 102 c, managing and storing contexts of theWTRUs 102 a, 102 b, 102 c, and the like.

The SGW 164 may be connected to the PGW 166, which may provide the WTRUs102 a, 102 b, 102 c with access to packet-switched networks, such as theInternet 110, to facilitate communications between the WTRUs 102 a, 102b, 102 c and IP-enabled devices.

The CN 106 may facilitate communications with other networks. Forexample, the CN 106 may provide the WTRUs 102 a, 102 b, 102 c withaccess to circuit-switched networks, such as the PSTN 108, to facilitatecommunications between the WTRUs 102 a, 102 b, 102 c and traditionalland-line communications devices. For example, the CN 106 may include,or may communicate with, an IP gateway (e.g., an IP multimedia subsystem(IMS) server) that serves as an interface between the CN 106 and thePSTN 108. In addition, the CN 106 may provide the WTRUs 102 a, 102 b,102 c with access to the other networks 112, which may include otherwired and/or wireless networks that are owned and/or operated by otherservice providers.

Although the WTRU is described in FIGS. 1A-1D as a wireless terminal, itis contemplated that in certain representative embodiments that such aterminal may use (e.g., temporarily or permanently) wired communicationinterfaces with the communication network.

In representative embodiments, the other network 112 may be a WLAN.

A WLAN in Infrastructure Basic Service Set (BSS) mode may have an AccessPoint (AP) for the BSS and one or more stations (STAs) associated withthe AP. The AP may have an access or an interface to a DistributionSystem (DS) or another type of wired/wireless network that carriestraffic in to and/or out of the BSS. Traffic to STAs that originatesfrom outside the BSS may arrive through the AP and may be delivered tothe STAs. Traffic originating from STAs to destinations outside the BSSmay be sent to the AP to be delivered to respective destinations.Traffic between STAs within the BSS may be sent through the AP, forexample, where the source STA may send traffic to the AP and the AP maydeliver the traffic to the destination STA. The traffic between STAswithin a BSS may be considered and/or referred to as peer-to-peertraffic. The peer-to-peer traffic may be sent between (e.g., directlybetween) the source and destination STAs with a direct link setup (DLS).In certain representative embodiments, the DLS may use an 802.11e DLS oran 802.11z tunneled DLS (TDLS). A WLAN using an Independent BSS (IBSS)mode may not have an AP, and the STAs (e.g., all of the STAs) within orusing the IBSS may communicate directly with each other. The IBSS modeof communication may sometimes be referred to herein as an “ad-hoc” modeof communication.

When using the 802.11ac infrastructure mode of operation or a similarmode of operations, the AP may transmit a beacon on a fixed channel,such as a primary channel. The primary channel may be a fixed width(e.g., 20 MHz wide bandwidth) or a dynamically set width via signaling.The primary channel may be the operating channel of the BSS and may beused by the STAs to establish a connection with the AP. In certainrepresentative embodiments, Carrier Sense Multiple Access with CollisionAvoidance (CSMA/CA) may be implemented, for example in in 802.11systems. For CSMA/CA, the STAs (e.g., every STA), including the AP, maysense the primary channel. If the primary channel is sensed/detectedand/or determined to be busy by a particular STA, the particular STA mayback off. One STA (e.g., only one station) may transmit at any giventime in a given BSS.

High Throughput (HT) STAs may use a 40 MHz wide channel forcommunication, for example, via a combination of the primary 20 MHzchannel with an adjacent or nonadjacent 20 MHz channel to form a 40 MHzwide channel.

Very High Throughput (VHT) STAs may support 20 MHz, 40 MHz, 80 MHz,and/or 160 MHz wide channels. The 40 MHz, and/or 80 MHz, channels may beformed by combining contiguous 20 MHz channels. A 160 MHz channel may beformed by combining 8 contiguous 20 MHz channels, or by combining twonon-contiguous 80 MHz channels, which may be referred to as an 80+80configuration. For the 80+80 configuration, the data, after channelencoding, may be passed through a segment parser that may divide thedata into two streams. Inverse Fast Fourier Transform (IFFT) processing,and time domain processing, may be done on each stream separately. Thestreams may be mapped on to the two 80 MHz channels, and the data may betransmitted by a transmitting STA. At the receiver of the receiving STA,the above described operation for the 80+80 configuration may bereversed, and the combined data may be sent to the Medium Access Control(MAC).

Sub 1 GHz modes of operation are supported by 802.11af and 802.11ah. Thechannel operating bandwidths, and carriers, are reduced in 802.11af and802.11ah relative to those used in 802.11n, and 802.11ac. 802.11afsupports 6 5 MHz, 10 MHz and 20 MHz bandwidths in the TV White Space(TVWS) spectrum, and 802.11ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and16 MHz bandwidths using non-TVWS spectrum. According to a representativeembodiment, 802.11ah may support Meter Type Control/Machine-TypeCommunications, such as MTC devices in a macro coverage area. MTCdevices may have certain capabilities, for example, limited capabilitiesincluding support for (e.g., only support for) certain and/or limitedbandwidths. The MTC devices may include a battery with a battery lifeabove a threshold (e.g., to maintain a very long battery life).

WLAN systems, which may support multiple channels, and channelbandwidths, such as 802.11n, 802.11ac, 802.11af, and 802.11ah, include achannel which may be designated as the primary channel. The primarychannel may have a bandwidth equal to the largest common operatingbandwidth supported by all STAs in the BSS. The bandwidth of the primarychannel may be set and/or limited by a STA, from among all STAs inoperating in a BSS, which supports the smallest bandwidth operatingmode. In the example of 802.11ah, the primary channel may be 1 MHz widefor STAs (e.g., MTC type devices) that support (e.g., only support) a 1MHz mode, even if the AP, and other STAs in the BSS support 2 MHz, 4MHz, 8 MHz, 16 MHz, and/or other channel bandwidth operating modes.Carrier sensing and/or Network Allocation Vector (NAV) settings maydepend on the status of the primary channel. If the primary channel isbusy, for example, due to a STA (which supports only a 1 MHz operatingmode), transmitting to the AP, the entire available frequency bands maybe considered busy even though a majority of the frequency bands remainsidle and may be available.

In the United States, the available frequency bands, which may be usedby 802.11ah, are from 902 MHz to 928 MHz. In Korea, the availablefrequency bands are from 917.5 MHz to 923.5 MHz. In Japan, the availablefrequency bands are from 916.5 MHz to 927.5 MHz. The total bandwidthavailable for 802.11ah is 6 MHz to 26 MHz depending on the country code.

FIG. 1D is a system diagram illustrating the RAN 113 and the CN 115according to an embodiment. As noted above, the RAN 113 may employ an NRradio technology to communicate with the WTRUs 102 a, 102 b, 102 c overthe air interface 116. The RAN 113 may also be in communication with theCN 115.

The RAN 113 may include gNBs 180 a, 180 b, 180 c, though it will beappreciated that the RAN 113 may include any number of gNBs whileremaining consistent with an embodiment. The gNBs 180 a, 180 b, 180 cmay each include one or more transceivers for communicating with theWTRUs 102 a, 102 b, 102 c over the air interface 116. In one embodiment,the gNBs 180 a, 180 b, 180 c may implement MIMO technology. For example,gNBs 180 a, 108 b may utilize beamforming to transmit signals to and/orreceive signals from the gNBs 180 a, 180 b, 180 c. Thus, the gNB 180 a,for example, may use multiple antennas to transmit wireless signals to,and/or receive wireless signals from, the WTRU 102 a. In an embodiment,the gNBs 180 a, 180 b, 180 c may implement carrier aggregationtechnology. For example, the gNB 180 a may transmit multiple componentcarriers to the WTRU 102 a (not shown). A subset of these componentcarriers may be on unlicensed spectrum while the remaining componentcarriers may be on licensed spectrum. In an embodiment, the gNBs 180 a,180 b, 180 c may implement Coordinated Multi-Point (CoMP) technology.For example, WTRU 102 a may receive coordinated transmissions from gNB180a and gNB 180 b (and/or gNB 180 c).

The WTRUs 102 a, 102 b, 102 c may communicate with gNBs 180 a, 180 b,180 c using transmissions associated with a scalable numerology. Forexample, the OFDM symbol spacing and/or OFDM subcarrier spacing may varyfor different transmissions, different cells, and/or different portionsof the wireless transmission spectrum. The WTRUs 102 a, 102 b, 102 c maycommunicate with gNBs 180 a, 180 b, 180 c using subframe or transmissiontime intervals (TTIs) of various or scalable lengths (e.g., containingvarying number of OFDM symbols and/or lasting varying lengths ofabsolute time).

The gNBs 180 a, 180 b, 180 c may be configured to communicate with theWTRUs 102 a, 102 b, 102 c in a standalone configuration and/or anon-standalone configuration. In the standalone configuration, WTRUs 102a, 102 b, 102 c may communicate with gNBs 180 a, 180 b, 180 c withoutalso accessing other RANs (e.g., such as eNode-Bs 160 a, 160 b, 160 c).In the standalone configuration, WTRUs 102 a, 102 b, 102 c may utilizeone or more of gNBs 180 a, 180 b, 180 c as a mobility anchor point. Inthe standalone configuration, WTRUs 102 a, 102 b, 102 c may communicatewith gNBs 180 a, 180 b, 180 c using signals in an unlicensed band. In anon-standalone configuration WTRUs 102 a, 102 b, 102 c may communicatewith/connect to gNBs 180 a, 180 b, 180 c while also communicatingwith/connecting to another RAN such as eNode-Bs 160 a, 160 b, 160 c. Forexample, WTRUs 102 a, 102 b, 102 c may implement DC principles tocommunicate with one or more gNBs 180 a, 180 b, 180 c and one or moreeNode-Bs 160 a, 160 b, 160 c substantially simultaneously. In thenon-standalone configuration, eNode-Bs 160 a, 160 b, 160 c may serve asa mobility anchor for WTRUs 102 a, 102 b, 102 c and gNBs 180 a, 180 b,180 c may provide additional coverage and/or throughput for servicingWTRUs 102 a, 102 b, 102 c.

Each of the gNBs 180 a, 180 b, 180 c may be associated with a particularcell (not shown) and may be configured to handle radio resourcemanagement decisions, handover decisions, scheduling of users in the ULand/or DL, support of network slicing, dual connectivity, interworkingbetween NR and E-UTRA, routing of user plane data towards User PlaneFunction (UPF) 184 a , 184 b , routing of control plane informationtowards Access and Mobility Management Function (AMF) 182 a, 182 b andthe like. As shown in FIG. 1D, the gNBs 180 a, 180 b, 180 c maycommunicate with one another over an Xn interface.

The CN 115 shown in FIG. 1D may include at least one AMF 182 a, 182 b,at least one UPF 184 a, 184 b, at least one Session Management Function(SMF) 183 a, 183 b, and possibly a Data Network (DN) 185 a, 185 b. Whileeach of the foregoing elements are depicted as part of the CN 115, itwill be appreciated that any of these elements may be owned and/oroperated by an entity other than the CN operator.

The AMF 182 a, 182 b may be connected to one or more of the gNBs 180 a,180 b, 180 c in the RAN 113 via an N2 interface and may serve as acontrol node. For example, the AMF 182 a, 182 b may be responsible forauthenticating users of the WTRUs 102 a, 102 b, 102 c, support fornetwork slicing (e.g., handling of different PDU sessions with differentrequirements), selecting a particular SMF 183 a, 183 b, management ofthe registration area, termination of NAS signaling, mobilitymanagement, and the like. Network slicing may be used by the AMF 182 a,182 b in order to customize CN support for WTRUs 102 a, 102 b, 102 cbased on the types of services being utilized WTRUs 102 a, 102 b, 102 c.For example, different network slices may be established for differentuse cases such as services relying on ultra-reliable low latency (URLLC)access, services relying on enhanced massive mobile broadband (eMBB)access, services for machine type communication (MTC) access, and/or thelike. The AMF 162 may provide a control plane function for switchingbetween the RAN 113 and other RANs (not shown) that employ other radiotechnologies, such as LTE, LTE-A, LTE-A Pro, and/or non-3GPP accesstechnologies such as WiFi.

The SMF 183 a, 183 b may be connected to an AMF 182 a, 182 b in the CN115 via an N11 interface. The SMF 183 a, 183 b may also be connected toa UPF 184 a, 184 b in the CN 115 via an N4 interface. The SMF 183 a, 183b may select and control the UPF 184 a, 184 b and configure the routingof traffic through the UPF 184 a, 184 b. The SMF 183 a, 183 b mayperform other functions, such as managing and allocating UE IP address,managing PDU sessions, controlling policy enforcement and QoS, providingdownlink data notifications, and the like. A PDU session type may beIP-based, non-IP based, Ethernet-based, and the like.

The UPF 184 a, 184 b may be connected to one or more of the gNBs 180 a,180 b, 180 c in the RAN 113 via an N3 interface, which may provide theWTRUs 102 a, 102 b, 102 c with access to packet-switched networks, suchas the Internet 110, to facilitate communications between the WTRUs 102a, 102 b, 102 c and IP-enabled devices. The UPF 184, 184 b may performother functions, such as routing and forwarding packets, enforcing userplane policies, supporting multi-homed PDU sessions, handling user planeQoS, buffering downlink packets, providing mobility anchoring, and thelike.

The CN 115 may facilitate communications with other networks. Forexample, the CN 115 may include, or may communicate with, an IP gateway(e.g., an IP multimedia subsystem (IMS) server) that serves as aninterface between the CN 115 and the PSTN 108. In addition, the CN 115may provide the WTRUs 102 a, 102 b, 102 c with access to the othernetworks 112, which may include other wired and/or wireless networksthat are owned and/or operated by other service providers. In oneembodiment, the WTRUs 102 a, 102 b, 102 c may be connected to a localData Network (DN) 185 a, 185 b through the UPF 184 a, 184 b via the N3interface to the UPF 184 a, 184 b and an N6 interface between the UPF184 a, 184 b and the DN 185 a, 185 b.

In view of FIGS. 1A-1D, and the corresponding description of FIGS.1A-1D, one or more, or all, of the functions described herein withregard to one or more of: WTRU 102 a-d, Base Station 114 a -b, eNode-B160 a-c, MME 162, SGW 164, PGW 166, gNB 180 a-c, AMF 182 a-b, UPF 184 a-b, SMF 183 a-b, DN 185 a-b, and/or any other device(s) describedherein, may be performed by one or more emulation devices (not shown).The emulation devices may be one or more devices configured to emulateone or more, or all, of the functions described herein. For example, theemulation devices may be used to test other devices and/or to simulatenetwork and/or WTRU functions.

The emulation devices may be designed to implement one or more tests ofother devices in a lab environment and/or in an operator networkenvironment. For example, the one or more emulation devices may performthe one or more, or all, functions while being fully or partiallyimplemented and/or deployed as part of a wired and/or wirelesscommunication network in order to test other devices within thecommunication network. The one or more emulation devices may perform theone or more, or all, functions while being temporarilyimplemented/deployed as part of a wired and/or wireless communicationnetwork. The emulation device may be directly coupled to another devicefor purposes of testing and/or may performing testing using over-the-airwireless communications.

The one or more emulation devices may perform the one or more, includingall, functions while not being implemented/deployed as part of a wiredand/or wireless communication network. For example, the emulationdevices may be utilized in a testing scenario in a testing laboratoryand/or a non-deployed (e.g., testing) wired and/or wirelesscommunication network in order to implement testing of one or morecomponents. The one or more emulation devices may be test equipment.Direct RF coupling and/or wireless communications via RF circuitry(e.g., which may include one or more antennas) may be used by theemulation devices to transmit and/or receive data.

The following acronyms may be used in connection with the descriptionprovided herein.

3GPP 3rd Generation Partnership Project

5GC 5G Core network

AMF Access and Mobility Management Function ATSSS Access TrafficSteering, Switching & Splitting EPC Evolved Packet Core EPS EvolvedPacket System E-UTRAN Evolved Universal Terrestrial Radio Access NetworkHSS Home Subscriber Server MA-PDU Multi-Access PDU Session MME MobilityManagement Entity N3IWF Non-3GPP InterWorking Function NR New Radio PCFPolicy Control Function PDU Protocol Data Unit PDN Packet Data NetworkPGW Serving Gateway PGW-C PDN Gateway SGW Serving Gateway SMF SessionManagement Function S-NSSAI Single Network Slice Selection AssistanceInformation UDM Unified Data Management URSP UE Route Selection Policy

A multi-access PDU session (MA-PDU) may be a PDU session that isassociated with multiple user plane connectivities including, forexample, connectivity via a 3GPP access network (e.g., 5G NR) andconnectivity via a non-3GPP access network (e.g. WLAN). A WTRU that hasestablished a MA-PDU may steer application traffic towards a 3GGP accessnetwork and/or a non-3GPP access network. The WTRU may switch or splitthe traffic between the two access networks, e.g., according to theconfigured ATSSS rules. FIG. 2 provides an illustration of an exampleMA-PDU. A MA-PDU may be terminated in a 5G Core Network (5GC). Forexample, the user plane resources for a 3GPP access network and anon-3GPP access network may be terminated in a user plane function (UPF)in the 5GC.

As shown in FIG. 2 , a WTRU 102 may access a 5GC network (hereinotherwise referred to as “5GC”) 115 using a non-3GPP access network(e.g., using a first radio technology) via a N3IWF 210. The WTRU 102 mayaccess the 5GC 115 using a 3GPP access network (e.g., using a secondradio technology) via a RAN 113 (or a RAN 104). A MA-PDU session 220 maybe established with respect to the WTRU 102 and a network (e.g., a DN185 such as shown in FIG. 1D or another network). The MA-PDU session 220may carry multiple flows (e.g., traffic flows) 222, 224 and 226 to the5GC 115. The UPF 184 may communicate these flows to the DN 185, such asover an N6 interface. For example, the MA-PDU session 220 may have anon-3GPP access 230 (e.g. via the N3IWF 210) and a 3GPP access 240(e.g., via the RAN 113. The WTRU 102 may send one or more flows (e.g.,flows 222 and 224) via a 3GPP access leg of the MA-PDU session 220 tothe RAN 113 using a first radio access technology (e.g., 5G NR). TheWTRU 102 may send one or more flows (e.g., flow 226) via a non-3GPPaccess leg of the MA-PDU session 220 to the N3IWF 210 using a secondradio access technology (e.g., IEEE 802.11). The flows may have separateQoS requirements associated therewith.

The 5GC 115 may have respective connections 250, 260, 270 to the RAN113, the N3IWF 260 and the UPF 184. For example, the N3IWF 210 may havean N2 interface to an AMF 182 of the 5GC 115.

In examples (e.g., during 5G network roll-out), 3GPP (e.g., a 5G NRnetwork) access coverage may not be available or sufficient in certainareas such as inside a building, but a 4G access network (e.g., an LTEnetwork connected to a 4G Core Network such as an EPC) and/or a non-3GPPaccess network (e.g., a non-3GPP access network connected to a 5G CoreNetwork) may be in good operating conditions in those areas. A WTRU 102may be able to benefit from the latter two access networks (e.g., LTEand non-3GPP access network) for traffic steering and/or switching, anda MA-PDU session 220 (e.g., which may have 3GPP access such as LTE inEPC and/or non-3GPP access in 5GC) may be supported. FIG. 3 illustratesan example MA-PDU session 220 with a PDN connection 304 in an EPCnetwork (herein otherwise referred to as “EPC) 306 (e.g., via 3GPP LTEaccess) as one access leg and a PDU session 302 in a 5GC 115 (e.g., vianon-3GPP access) as another access leg.

As shown in FIG. 3 , a non-roaming architecture may be used forinterworking between the 5GC 115 via non-3GPP access (e.g., anon-3GPP-access network 308) and the EPC 306 via 3GPP access (e.g., anE-UTRA network (E-UTRAN) 310). The WTRU 102 may use a first radio accesstechnology for non-3GPP access via the N3IWF 210 to communicate with the5GC 115. The WTRU 102 may use a second radio access technology for 3GPPaccess via the E-UTRAN 310 to communicate with the EPC 306. Such anarchitecture may support one or more MA-PDU sessions, such as the MA-PDUsession 220 with a 3GPP access leg in the EPC 306 (e.g., an access legmay refer to the resources including user plane resources associatedwith accessing a network). The MA-PDU session 220 may be establishedwith respect to the WTRU 102 and a DN 185 outside of the 5GC 115 asshown in FIG. 3 or a DN 185 or another network such as shown in FIG. 1D.For purposes of explanation, the UPF 184 and the DN 185 are shownseparately from the 5GC 115 in FIG. 2 . It should be understood that theUPF 184 and/or DN 185 may reside in the 5GC 115 as shown in FIG. 1D. Asanother example, the MA-PDU session 220 may have a DN 185 that residesoutside of the 5GC 115 and/or the EPC 306 as shown in FIG. 3 . Thesearchitectures may be used in the examples provided herein.

The EPC 306 may include an MME 162 and a SGW 314 which may be connectedover an S11 interface. The MME 162 may be connected to the E-UTRAN 310over an S1-MME interface. The SGW 314 may be connected to the E-UTRAN310 over an S1-U interface. THE 5GC 115 may include an AMF 182 which maybe connected to the N3IWF 210 over an N2 interface. A UPF and PGW for auser plane (UPF+PGW-U) 316 may be provided for the PDN connection 304and the PDU session 302 to the data network (e.g., the MA-PDU session220). The UPF+PGW 316 may be connected to the SGW 314 over an S5-Uinterface. The UPF+PGW 316 may be connected to the NWIWF 210 over an N3interface. A SMF and PGW for a control plane (SMF+PGW-C) 818 may beconnected to the SGW 314 over an S5-C interface. The SMF+PGW-C 818 maybe connected to the AMF 182 over an N11 interface. The SMF+PGW-C 818 maybe connected to the UPF+PGW-U 316 over an N4 interface. A PCF 320 may beconnected to the AMF 182 by a N15 interface. The PCF 320 may beconnected to the SMF+PGW-C 318 by a N7 interface. A HSS+UDM 322 may beconnected to the SMF+PGW-C 318 by a N10 interface.

An MA-PDU session 220 with a 3GPP access leg may be established in theEPC 306. The MA-PDU session 220 may be associated with multiple (e.g.,two) access network types (e.g., a RAN and WLAN) and/or multiple 3GGPcore networks (e.g., EPC 306 and 5GC 115). A PDN connection 304 in theEPC 306 (e.g., via 3GGP access) and a PDU session 302 in the 5GC 115(e.g., via non-3GPP access) may be established. The EPC PDN connection304 and the 5G PDU session 302 may be associated with each other, forexample, to provide traffic steering and/or traffic switchingfunctionalities. Shared network entities between multiple (e.g., two)types of core networks, such as SMF+PGW-C, UPF+PGW-U and/or HSS+UDM, maymake it possible for the core networks to handle the MA-PDU session 220described herein as well as the related traffic steering and/orswitching in the same network entities.

The following aspects may be considered in connection with establishinga MA-PDU session 220 as described herein. These aspects may include, forexample, how a MA-PDU session 220 with a 3GGP access leg in the EPC 306is triggered (e.g., how and/or when a WTRU 102 may determine toestablish such a MA-PDU session 220), how and/or when a WTRU 102establishes a new PDN connection 304 or identify a suitable existing PDNconnection 304 in the EPC 306 for the MA-PDU session 220, how a WTRU 102associates a PDN connection 304 with a PDU session 302 in the 5GC 115and how the WTRU 102 implements traffic steering and/or switchingfunctionalities on the PDN connection 304 and/or the PDU session 302,what the QoS requirements are for traffic flows that are coordinatedbetween an EPC PDN connection 304 and a 5GC PDU session 302, etc.

With respect to the triggering of a MA-PDU session 220 with 3GGP accessin the EPC 306, a WTRU 102 may determine whether such a MA-PDU session220 with 3GGP access leg in the EPC 306 can be established. URSP rulesmay be configured (e.g., preconfigured) for the WTRU 102 and may includean indication for establishing a MA-PDU session 220. The URSP rules mayindicate, for example, that 3GGP access in the EPC 306 is allowed forroute selection descriptors that have an access type preference ofmulti-access. The URSP rules may indicate the respective priorities ofusing 3GGP access leg in the EPC 306 and in the 5GC 115 for the MA-PDUsession 220. Default priorities may be specified. For example, when 3GGPaccess in the 5GC 115 is available, it may be given a higher prioritythan 3GGP access in the EPC 306 for establishing the MA-PDU session 220.

In examples (e.g., when a WTRU 102 reports that it supports MA-PDUsessions with a 3GGP access leg in the EPC 306, such as during aregistration procedure), the network may update the URSP rules for aWTRU 102, for example, with the indications described herein. The updatemay be performed, for example, using a WTRU configuration updateprocedure (e.g., such as the UE Configuration Update procedure definedfor 5G).

In examples (e.g., when a new PDU session is to be established forapplication traffic), a WTRU 102 may check one or more of the followingcriteria to determine whether a MA-PDU session 220 with 3GGP access inthe EPC 306 may be established.

The WTRU 102 may check its registration status in the EPC 306 todetermine whether a MA-PDU session 220 with 3GGP access in the EPC 306may be established. The WTRU 102 may be registered in a 5GC 115 and anEPC 306in order to be able to establish a MA-PDU session 220. As such,the WTRU 102 may be operating in a dual-registration mode. The WTRU 102and/or the network may choose the dual-registration mode for 5GC-EPCinterworking, for example, during 5GC registration and/or EPC trackingarea update procedures (e.g., if the WTRU 102 reports a capability forsupporting MA-PDU sessions with a 3GGP access leg in the EPC 306). Inexamples (e.g., when the WTRU 102 determines to establish a MA-PDUsession 220 with 3GGP access leg in the EPC 306, and/or when anEPC/E-UTRAN network is available but the WTRU 102 has not registeredwith the EPC 306), the WTRU 102 may initiate an attach procedure withthe EPC 306 first.

The WTRU 102 may check its own and/or the network's capabilities forsupporting MA-PDU sessions with 3GGP access in the EPC 306 to determinewhether a MA-PDU session 220 with 3GGP access in the EPC 306 may beestablished. The WTRU 102 may report its capabilities for supportingMA-PDU sessions with 3GGP access leg in the EPC 306. The reporting maybe performed during a 5GC registration procedure and/or an EPC attachprocedure. The network (e.g., the 5GC 115 and/or the EPC 306) mayindicate (e.g., return to the WTRU 102) the network's capabilities forMA-PDU sessions. In examples, the WTRU 102 may establish a MA-PDUsession 220 when (e.g., only when) the WTRU 102, the 5GC 115, and theEPC 306 have the capabilities to support MA-PDU sessions with 3GGPaccess in the EPC 306.

The WTRU 102 may determine whether a MA-PDU session 220 with 3GGP accessin the EPC 306 can be established based on URSP rules (e.g., URSP ruleindications). For example, the WTRU 102 may establish a MA-PDU session220 when the route selection descriptor associated with triggeringapplication traffic include an access type preference set asmulti-access and/or when the URSP rules include an indication that 3GGPaccess leg in the EPC 306 is allowed. When multiple access types areavailable (e.g., when 3GGP access is available for both a 5GC 115 (e.g.,NR) and a EPC 306 (e.g., E-UTRAN)), the WTRU 102 may check thepriorities of the multiple access types. For example, if 3GGP access inthe EPC 306 has a higher priority, the WTRU 102 may establish a MA-PDUsession 220 with 3GGP access leg in the EPC 306.

A WTRU 102 may establish a MA-PDU session 220 with 3GGP access leg inthe EPC 306 based on one or more of the following, for example, when allor a subset of the criteria described above are satisfied.

In examples, the WTRU 102 may identify a suitable PDN connection 304 inthe EPC 306. The WTRU 102 may then establish a MA-PDU session 220 in the5GC 115 and associate the existing PDU with the MA-PDU session 220. Inexamples, the WTRU 102 may already have a MA-PDU session 220 (e.g., anormal MA-PDU) session established in the 5GC 115, and the MA-PDUsession 220 may have a 3GGP access leg and a non-3GPP access leg in the5GC 115. The WTRU 102 may replace the 3GGP access leg in the 5GC 115with a suitable PDN connection 304 in the EPC 306. In examples, the WTRU102 may request (e.g., with a network) to establish an access PDUsession 302 (e.g., a single access PDU session) in the 5GC 115 vianon-3GPP access, and the 5GC 115 may decide to upgrade the requested PDUsession 302 to a MA-PDU session 220 with a 3GGP access leg in the EPC306.

With respect to associating a suitable PDN connection 304 in the EPC 306with a 5GC MA-PDU session 220, a WTRU 102 may determine to establish aMA-PDU session 220 with 3GGP access leg in the EPC 306. The WTRU 102 maysearch among existing PDN connections to see if there is a suitable PDNconnection 304 that meets one or more of the following criteria. One ofthe criteria may be whether the type of the PDN connection (e.g., IPv6,IPv4v6 or Ethernet) matches that of the MA-PDU session 220. One of thecriteria may be whether an access point name (APN) of the PDN connection304 corresponds to a data network name (DNN) of the MA-PDU session 220.One of the criteria may be whether the PDN connection 304 wasestablished to support 5GC-EPC interworking and/or whether a PDU sessionID has been allocated for the PDN connection 304. One of the criteriamay be whether the S-NSSAI(s) that the WTRU 102 receives from a sharednetwork entity (e.g., PGW-C+SMF) matches that of the MA-PDU session 220.

If a suitable PDN connection 304 is identified, the WTRU 102 mayinitiate a MA-PDU session establishment procedure via non-3GPP access inthe 5GC 115. The WTRU 102 may perform one or more of the followingduring this procedure.

The WTRU 102 may indicate in a PDU session establishment request that a3GGP access leg is available in the EPC/E-UTRAN. As such, the networkmay skip establishing user plane resources over the 3GGP access of the5GC 115.

The WTRU 102 may use the PDU session ID allocated for a PDN connection304 as the PDU session ID of the MA-PDU session 220 and set a requesttype to indicate that it is associated with an existing PDU session 302.

The WTRU 102 may provide the APN of the PDN connection 304 in the PDUsession establishment request. The 5GC 115 may use the APN to locate ashared network entity (e.g., PGW-C+SMF) that may be serving the PDNconnection 304 and select the same entity (e.g., same PGW-C+SMF) for theMA-PDU session 220.

The WTRU 102 may provide the IP address of the PDN connection 304 (e.g.,to the network) and the network may use the same IP address for theMA-PDU session 220.

In response to the MA-PDU session 220 being successfully established,the WTRU 102 may maintain one or more identifiers of the PDN connection304 (e.g., the EPS bearer ID (EBI) of a default bearer in the PDNconnection, the APN, etc.), for example, in the WTRU's local sessioncontext of the MA-PDU session 220. The WTRU 102 may mark in the contextthat the 3GGP access leg of this MA-PDU session 220 points to the PDNconnection 304.

During a traffic steering or switching process (e.g., when ATSSS ruleevaluation results point to or indicate 3GGP access), a WTRU 102 maysend data over an associated PDN connection 304 in the EPC 306.

FIG. 4 illustrates example high-level operations that may be performedby a WTRU 102 and/or a network in accordance with the examples describedherein.

At 401, a WTRU 102 (e.g., a dual-registration mode WTRU) may perform anattach procedure (e.g., an initial attach procedure) with an EPC 306(e.g., the MME 162) and/or may indicate (e.g., to the EPC 306 such asthe MME 162) that the WTRU 102 is moving from the 5GC 115. At 402, theWTRU 102 may establish a PDN connection 304 (e.g., with a network entitysuch as the SMF+PGW-C 318) in an EPC 306 that supports 5GC-EPCinterworking. The WTRU 102 may be allocated a PDU session ID for thisPDN connection 304 and may provide the PDU session ID to the network(e.g., a network entity such as the SMF+PGW-C 318). At 403 (e.g., afterthe PDN connection 304 has been successfully established), the MME 162may notify the HSS+UDM 322 of the APN+PGW-C pair (e.g., the APNidentifier and the PDU session identifier) that corresponds to the PDNconnection. At 404, the WTRU 102 may register with the 5GC 115 (e.g.,via non-3GPP access). The WTRU 102 may perform a registration procedurewith the AMF 182. The WTRU 102 and the 5GC 115 may exchange informationregarding their capabilities for supporting MA-PDU sessions with 3GGPaccess in the EPC 306.

At 405, MA-PDU session establishment may be triggered in the WTRU 102(e.g., the WTRU 102 may allow or prefer a 3GGP access leg in the EPC306). At 406, the WTRU 102 may search among existing (e.g., anyexisting) PDN connections and identify a suitable PDN connection thatmatches a desired MA-PDU session 220, e.g., according to the criteriadescribed herein.

At 407, the WTRU 102 may initiate (e.g., send) a PDU sessionestablishment request message over non-3GPP access (e.g., a non-3GPPaccess network) with an indication of multi-access and/or an indicationthat the 3GGP access leg is in the EPC 306. The WTRU 102 may provide(e.g., to the network) the PDU session ID allocated for the suitable PDNconnection 304, the DNN that corresponds to the APN of the PDNconnection 304, and/or the APN itself.

At 408, the AMF may retrieve the session manage context from theHSS+UDM. The context may include the APN and PGW-C addresses (e.g., as apair). The AMF may be able to locate the same PGW-C+SMF that serves thePDN connection 304, e.g., by comparing the APN received from the WTRU102 and the APN+PGW-C pairs received from the HSS+UDM.

At 409, the AMF may invoke the SMF service to create the PDU session(e.g. MA-PDU session 220) and/or its user plane resources. The SMF mayunderstand that a 3GGP access leg is already established in the EPC 306.The SMF may establish (e.g., only establish) user plane resources overnon-3GGP access in the 5GC 115.

At 410, the WTRU 102 may receive a PDU session establishment acceptmessage. The message may confirm that the MA-PDU session 220 has beensuccessfully set up. The WTRU 102 may receive ATSSS rules and/or QoSrules in the message.

At 411, the WTRU 102 may associate (e.g., locally associate) the PDNconnection 304 with the MA-DPU session context. Data may be sent overthe PDN connection 304, e.g., when the execution of the ATSSS rulespoints to the 3GGP access.

With respect to replacing a 3GGP access leg in a 5GC MA-PDU session 220with a suitable PDN connection 304, it may be assumed that a WTRU 102 isregistered with the 5GC 115 and/or has established a normal MA-PDUsession (e.g., a MA-PDU session with a 3GGP access leg and a non-3GPPaccess leg in the 5GC 115). In examples (e.g., when the 3GGP access inthe 5GC 115 is lost), the WTRU 102 may establish a PDN connection 304that corresponds to the 5GC 3GGP access leg of the MA-PDU session 220.The WTRU 102 may (e.g., alternatively) identify an existing suitable PDNconnection 304 as described herein. The WTRU 102 may replace the 3GGPaccess leg of the MA-PDU session 220 with the new PDN connection 304.

The WTRU 102 may establish a PDN connection 304 in the EPC 306 thatcorresponds to the original 3GGP access leg (in the 5GC 115) of theMA-PDU session 220. The WTRU 102 may perform one or more of thefollowing.

The WTRU 102 may indicate, e.g., in a PDN connectivity request to theEPC 306, that the PDN connection 304 is part of a MA-PDU session 220.

After the PDN connection 304 is established, the network may understandthat the PDN connection 304 is used as a leg of a MA-PDU session 220 andmay not release the corresponding PDU session 302 in the 5GC 115.

After the PDN connection 304 is successfully established, the WTRU 102may perform a PDU session modification procedure to inform the 5GC 115that it should associate the PDN connection 304 with the MA-PDU session220. One or more of the following may take place during the PDU sessionmodification procedure. The WTRU 102 may indicate that the purpose ofthe PDU session modification is to replace the 3GGP access leg with aPDN connection 304. The WTRU 102 may provide the APN of the PDNconnection 304 to the 5GC 115. The 5GC network may associate the PDNconnection 304 to the MA-PDU session 220 (e.g., if the modificationprocedure is successful).

FIG. 5 illustrates example high-level operations that may be performedby a WTRU 102 and/or a network in accordance with the examples describedherein.

At 501, a WTRU 102 (e.g., a dual-registration mode WTRU) may registerwith a 5GC 115. At 502, the WTRU 102 may establish a MA-PDU session 220(e.g., a normal MA-PDU session) in the 5GC 115 with a 3GGP access legand a non-3GPP access leg in the 5GC 115. At 503, the WTRU 102 maydetect that it has lost the 3GGP access leg (e.g., NR) and may reportthe unavailability of the 3GGP access to a network.

At 504 a , the WTRU 102 may perform attach and PDN connectivityestablishment in the EPC 306 (e.g., if the WTRU 102 supports MA-PDUsessions with a 3GGP access leg in the EPC 306). The WTRU 102 mayprovide the PDU session ID of the MA-PDU session 220 to the EPC 306. At504 b (e.g., if the WTRU 102 has already established a suitable PDNconnection 304 in the EPC 306), the WTRU 102 may identify such asuitable existing PDN connection 304 as described herein.

At 505 (e.g., after a suitable PDN connection is established oridentified), the WTRU 102 may initiate a PDU session modificationprocedure with the 5GC 115. The WTRU 102 may indicate in a request thatthe 3GGP access leg of the MA-PDU session 220 may be replaced by the PDNconnection 304 in the EPC 306. The WTRU 102 may provide the APN of thePDN connection 304 to the 5GC 115.

At 506, the SMF may modify the DL traffic forwarding rules in the UPF.The traffic that is supposed to be forwarded on the 3GGP access may besent on the PDN connection 304. At 507, the WTRU 102 may receive a PDUmodification command from the network. At 508, the WTRU 102 mayassociate (e.g., locally associate) the PDN connection 304 with theMA-DPU session context. Data may be sent over the PDN connection 304,for example, when the execution of the ATSSS rules points to the 3GGPaccess.

With respect to a network upgrading a single-access PDU request to aMA-PDU session 220 with 3GGP access in the EPC 306, a WTRU 102 mayrequest the single-access PDU session 302 in the 5GC 115 via non-3GPPaccess. The WTRU 102 may indicate (e.g., to the network) itscapabilities for supporting MA-PDU sessions with 3GGP access in the EPC306. The 5GC 115 may decide to modify the PDU session 302 to a MA-PDUsession 220. The 5GC 115 may indicate in a PDU session accept messagethat the PDU Session 302 has been upgraded to MA-PDU session 220 (e.g.,by including one or more ATSSS rules in the message). The 5GC 115 may(e.g., additionally) indicate that the 3GGP access leg in the EPC 306 isallowed for the MA-PDU session 220.

The WTRU 102 may initiate, e.g., in response to receiving an indicationthat a 3GGP access leg in the EPC 306 is allowed, an attach and/or PDNconnectivity request procedure to establish a suitable PDN correspondingto the MA-PDU session 220. The WTRU 102 may identify, e.g., in responseto receiving an indication that a 3GGP access leg in the EPC 306 isallowed, an existing suitable PDN connection 304 and utilize the PDUsession modification procedure to inform the network that it shouldassociate the PDN connection 304 with the MA-PDU session 220 (e.g., inmanners described herein).

FIG. 6 illustrates example high-level operations that may be performedby a WTRU 102 and/or a network in accordance with the examples describedherein. At 601, a WTUR (e.g., a dual-registration mode WTRU) mayregister with a 5GC 115. At 602, the WTRU 102 may submit a single-accessPDU establishment request. At 603, the network may upgrade thesingle-access PDU session 302 to a MA-PDU session 220 with 3GGP accessin the EPC 306 and may send a PDU session establishment accept messageto the WTRU 102 indicating that the PDU session 302 has been upgraded toa MA-PDU session and/or that 3GGP access in the EPC 306 is allowed. At604, operations similar to those depicted at 504-508 of FIG. 5 may beperformed.

FIG. 7 is a diagram illustrating a representative procedure that may beimplemented by a WTRU 102 to replace a 3GGP access leg of a MA-PDUsession 220 with a PDN connection 304. As shown in FIG. 7 , theprocedure 700 may be implemented by the WTRU 102 to manage a MA-PDUsession 220 which includes a first access leg in a first network and asecond access leg in the first network. At 710, the WTRU 102 may performsending of information indicating that a PDN connection 304 (e.g., a newPDN connection or an existing PDN connection) in a second network is toreplace the second access leg (e.g., in the first network) of the MA-PDUsession 220. For example, the SMF+PGW-C 318 and the UPF+PGW-U 316 mayperform an N4 session modification. DL traffic rules may be modified sothat traffic is forwarded (e.g., sent) on the PDN connection 304 whichreplaces the 3GGP access leg. At 720, the WTRU 102 may perform receivingof information indicating an association of the second access leg of theMA-PDU session 220 with the PDN connection 304 in the second network.For example, the association of the of the second access leg of theMA-PDU session 220 with the PDN connection 304 may inform the WTRU 102that SMF+PGW-C 318 has modified the traffic rules for the MA-PDUsession. At 730, the WTRU 102 may perform sending of uplink data for theMA-PDU session 220 (e.g., to a data network destination) via the PDNconnection 304 in the second network. In addition to or in thealternative, the WTRU 102 may perform receiving of downlink data for theMA-PDU session 220 (e.g., from the data network destination) via the PDNconnection 304 in the second network.

In certain representative embodiments, the MA-PDU session 220 may have,prior to replacement of the second access leg with the PDN connection304, a non-3GPP access leg and a 3GGP access leg in the 5GC 115. TheWTRU 102 may use a first radio access technology to communicate over thenon-3GPP access leg (e.g., via the N31WF) in a first network (e.g., the5GC) and may use a second radio access technology to communicate overthe 3GGP access leg (e.g., via a gNB) in the first network (e.g., the5GC).

In certain representative embodiments, the WTRU 102 may perform aprocedure (e.g., request) to establish the MA-PDU session 220 with thefirst network (e.g., the 5GC). For example, the WTRU 102 may send a PDUsession establishment request to establish the MA-PDU session 220 priorto sending information which indicates that the PDN connection 304 inthe second network is to replace an access leg (e.g., 3GGP access leg)of the MA-PDU session 220. The information which indicates that the PDNconnection 304 in the second network is to replace the access leg of theMA-PDU session 220 may be transmitted via the N3IWF to the first network(e.g., the 5GC).

In certain representative embodiments, the WTRU 102 may perform aprocedure (e.g., request) to establish the PDN connection 304 with thesecond network (e.g., the EPC). For example, the WTRU 102 may send arequest to establish the PDN connection 304 prior to sending informationwhich indicates that the PDN connection 304 in the second network is toreplace an access leg (e.g., 3GGP access leg) of the MA-PDU session 220.As another example, the WTRU 102 may send a request to establish the PDNconnection 304 (e.g., a PDN connectivity request) and the request mayinclude the information which indicates that the PDN connection 304 inthe second network is to replace an access leg (e.g., 3GGP access leg)of the MA-PDU session 220. The request to establish the PDN connection304 may include a PDU session identifier for the MA-PDU session 220, anidentifier of an APN associated with the MA-PDU session 220 and/or anidentifier of the DNN associated with the APN.

In certain representative embodiments, the WTRU 102 may performcommunications using the modified MA-PDU session 220. For example, theWTRU 102 may transmit uplink data using the non-3GGP access leg, the PDNconnection 304 which replaced the 3GGP access leg, or both. The WTRU 102may determine the transmission path (e.g., non-3GPP access leg and/orPDN connection 304) based on any of an ATSSS rule(s) and/or a QoSrule(s). As another example, the WTRU 102 may receive downlink datausing the non-3GPP access leg, the PDN connection 304 which replaced the3GGP access leg, or both.

FIG. 8 is a diagram illustrating a representative procedure that may beimplemented by a WTRU 102 to associate a PDN connection 304 with aMA-PDU session 220. As shown in FIG. 8 , the procedure 800 may beimplemented by the WTRU 102. At 810, the WTRU 102 may perform sending ofa MA-PDU session establishment request to a first network. The MA-PDUsession establishment request may include information indicating a PDNconnection 304 in a second network. At 820, the WTRU 102 may performreceiving of a PDU session establishment accept message from the firstnetwork. The PDU session establishment accept message may includeinformation indicating the MA-PDU session 220 is established. At 830,the WTRU 102 may perform the WTRU 102 may perform sending of uplink datafor the MA-PDU session 220 (e.g., to a data network destination) via thePDN connection 304 in the second network. In addition to or in thealternative, the WTRU 102 may perform receiving of downlink data for theMA-PDU session 220 (e.g., from the data network destination) via the PDNconnection 304 in the second network.

In certain representative embodiments, the MA-PDU session 220 may have anon-3GPP access leg in the 5GC 115 and a 3GGP access leg in the EPC 306.The WTRU 102 may use a first radio access technology to communicate(e.g., via the N3IWF 210) over the non-3GPP access leg and may use asecond radio access technology to communicate (e.g., via a E-UTRAN 310)over the 3GGP access leg.

In certain representative embodiments, the WTRU 102 may perform aprocedure (e.g., request) to establish the MA-PDU session 220 with thefirst network (e.g., the 5GC 115). For example, the WTRU 102 may send aPDU session establishment request to establish the MA-PDU session 220.The PDU session establishment request may include information whichindicates any of the MA-PDU session 220 has 3GGP access to the EPC 306,an identifier (e.g., PDU session identifier) of the PDN connection 304,an identifier of an APN associated with the MA-PDU session 220 and/or anidentifier of the DNN associated with the APN.

In certain representative embodiments, the WTRU 102 may perform aprocedure (e.g., request) to establish the PDN connection 304 with thesecond network (e.g., the EPC). For example, the WTRU 102 may send arequest (e.g., PDN connectivity request) to establish the PDN connection304 prior to performing the procedure (e.g., request) to establish theMA-PDU session 220 with the first network (e.g., the 5GC). In responseto the request, the WTRU may receive a PDU session identifier and/or anAPN identifier as shown at 402 in FIG. 4 .

In certain representative embodiments, the WTRU 102 may performcommunications using the MA-PDU session 220 (e.g., after receiving thePDU session accept message). For example, the WTRU 102 may transmituplink data using a non-3GPP access leg, the PDN connection 304, orboth. The WTRU 102 may determine the transmission path (e.g., non-3GPPaccess leg and/or PDN connection 304) based on any of an ATSSS rule(s)and/or a QoS rule(s). As another example, the WTRU 102 may receivedownlink data using the non-3GPP access leg, the PDN connection 304, orboth.

FIG. 9 is a diagram illustrating a representative procedure that may beimplemented by a WTRU 102 to upgrade a single-access PDU session to aMA-PDU session 220 with a 3GGP access leg in an EPC. As shown in FIG. 9, the procedure 900 may be implemented by the WTRU 102. At 910, the WTRU102 may perform sending of a single-access PDU session establishmentrequest to a first network using a first radio access technology. At920, the WTRU 102 may perform receiving of a PDU session establishmentaccept message. The PDU session establishment accept message may includeinformation indicating that a MA-PDU session 220 is established. TheMA-PDU session 220 may include a first access leg and a second accessleg. The first access leg and the second access leg may be in a firstnetwork (e.g., the 5GC 115). At 930, the WTRU 102 may perform sending ofinformation indicating that a PDN connection 304 in a second network isto replace the second access leg (e.g., in the first network) of theMA-PDU session 220. At 940, the WTRU 102 may perform receiving of a PDUsession modification message. The PDU session modification message mayinclude information indicating an association of the second access legof the MA-PDU session 220 with the PDN connection 304. At 950, the WTRU102 may perform sending of uplink data for the MA-PDU session 220 (e.g.,to a data network destination) via the PDN connection 304 in the secondnetwork. In addition to or in the alternative, the WTRU 102 may performreceiving of downlink data for the MA-PDU session 220 (e.g., from thedata network destination) via the PDN connection 304 in the secondnetwork.

In certain representative embodiments, the MA-PDU session 220 may have anon-3GPP access leg in the 5GC 115 and a 3GGP access leg in the EPC 306.The WTRU 102 may use a first radio access technology to communicate(e.g., via the N3IWF 210) over the non-3GPP access leg and may use asecond radio access technology to communicate (e.g., via a E-UTRAN 310)over the 3GGP access leg.

In certain representative embodiments, the WTRU 102 may perform aprocedure (e.g., request) to establish the MA-PDU session 220 with thefirst network (e.g., the 5GC). For example, the WTRU 102 may send asingle-access PDU session establishment request and may receive the PDUsession establishment message indicating the establishment of the MA-PDUsession 220 prior to sending information which indicates that the PDNconnection 304 in the second network is to replace an access leg (e.g.,3GGP access leg) of the MA-PDU session 220. The information whichindicates that the PDN connection 304 in the second network is toreplace the access leg of the MA-PDU session 220 may be transmitted viathe N3IWF to the first network (e.g., the 5GC).

In certain representative embodiments, the WTRU 102 may perform aprocedure (e.g., request) to establish the PDN connection 304 with thesecond network (e.g., the EPC). For example, the WTRU 102 may send arequest to establish the PDN connection 304 prior to sending informationwhich indicates that the PDN connection 304 in the second network is toreplace an access leg (e.g., 3GGP access leg) of the MA-PDU session 220.As another example, the WTRU 102 may send a request to establish the PDNconnection 304 (e.g., a PDN connectivity request) and the request mayinclude the information which indicates that the PDN connection 304 inthe second network is to replace an access leg (e.g., 3GGP access leg)of the MA-PDU session 220. The request to establish the PDN connection304 may include a PDU session identifier for the MA-PDU session 220, anidentifier of an APN associated with the MA-PDU session 220 and/or anidentifier of the DNN associated with the APN.

In certain representative embodiments, the WTRU 102 may performcommunications using the modified MA-PDU session 220. For example, theWTRU 102 may transmit uplink data using the non-3GGP access leg, the PDNconnection 304 which replaced the 3GGP access leg, or both. The WTRU 102may determine the transmission path (e.g., non-3GPP access leg and/orPDN connection 304) based on any of an ATSSS rule(s) and/or a QoSrule(s). As another example, the WTRU 102 may receive downlink datausing the non-3GPP access leg, the PDN connection 304 which replaced the3GGP access leg, or both.

FIG. 10 is a diagram illustrating a representative procedure that may beimplemented by a network entity (NE) to replace a 3GGP access leg of aMA-PDU session with a PDN connection. As shown in FIG. 10 , theprocedure 1000 may be implemented by a NE (e.g., an SMF 183 and/or anSMF+PGW-C 318) which may be in communication with a WTRU 102. At 1010,the NE may receive, from the WTRU 102, information indicating that apacket data network (PDN) connection 304 (e.g., a new PDN connection oran existing PDN connection) in a network (e.g., the EPC 306) is toreplace the second (e.g., 3GGP) access leg of a MA-PDU session 220. At1020, the NE may proceed to configure traffic rules for the MA-PDUsession 220 which associate the second access leg of the MA-PDU session220 with the PDN connection 304. For example, the SMF+PGW-C 318 and theUPF+PGW-U 316 may perform an N4 session modification. For example, theconfiguring (e.g., reconfiguring) may modify the traffic forwardingrules (e.g., DL forwarding rules) in the UPF. The traffic that is to beforwarded on the 3GGP access leg may be sent on the PDN connection 304.At 1030, the NE may proceed to send, to the WTRU 102, a PDU sessionmodification message. The PDU session modification message may includeinformation indicating an association of the second access leg of theMA-PDU session 220 with the PDN connection 304. For example, theinformation in the PDU Session Modification message may inform the WTRU102 that data (e.g., uplink data) may be sent for the MA-PDU session 220over the associated PDN connection 304 in the EPC 306. The WTRU 102 mayassociate (e.g., locally associate) the PDN connection 304 with theMA-DPU session context. Data may be sent over the PDN connection 304,for example, when the execution of the ATSSS rules points to the 3GGPaccess.

FIG. 11 is a diagram illustrating a representative procedure that may beimplemented by a NE to associate a PDN connection with a MA-PDU session.As shown in FIG. 11 , the procedure 1100 may be implemented by a NE(e.g., an SMF 183 and/or an SMF+PGW-C 318) which may in communicationwith a WTRU 102. At 1110, the NE may receive a multi-access protocoldata unit (MA-PDU) session establishment request in a first network(e.g., the 5GC 115) for the WTRU. The MA-PDU session establishmentrequest may include information indicating a PDN connection 304 in asecond network (e.g., the EPC 306). At 1120, the NE may proceed toestablish a MA-PDU session having a first access leg in the firstnetwork and the PDN connection 304 (as a second access leg) in thesecond network based on the MA-PDU session establishment request. At1130, the NE may proceed to configure traffic rules which associate thesecond access leg of the MA-PDU session 220 with the PDN connection 304.For example, the SMF+PGW-C 318 and the UPF+PGW-U 316 may perform an N4session modification. For example, the configuring (e.g., reconfiguring)may modify the traffic forwarding rules (e.g., DL forwarding rules) inthe UPF. The traffic that is to be forwarded on the 3GGP access leg maybe sent on the PDN connection 304. At 1140, the NE may proceed to send,to the WTRU 102, a MA-PDU session establishment accept message (e.g.,from the first network). The MA-PDU session establishment accept messagemay include information indicating the MA-PDU session is established.For example, the information in the MA-PDU session establishment acceptmessage may inform the WTRU 102 that data (e.g., uplink data) may besent for the MA-PDU session 220 over the associated PDN connection 304in the EPC 306. The WTRU 102 may associate (e.g., locally associate) thePDN connection 304 with the MA-DPU session context. Data may be sentover the PDN connection 304, for example, when the execution of theATSSS rules points to the 3GGP access.

FIG. 12 is a diagram illustrating a representative procedure that may beimplemented by a NE to upgrade a single-access PDU session to a MA-PDUsession with a 3GGP access leg in an EPC. As shown in FIG. 12 , theprocedure 1200 may be implemented by a NE (e.g., an SMF 183 and/or anSMF+PGW-C 318) which may in communication with a WTRU 102. At 1210, theNE may receive a single-access protocol data unit (PDU) sessionestablishment request for a WTRU 102. At 1220, the NE may proceed toestablish a MA-PDU session in a having a first access leg in a firstnetwork (e.g., the 5GC 115) and a second access leg in the first networkbased on the single-access PDU session establishment request. At 1230,the NE may proceed to send a PDU session establishment accept message(e.g., to the WTRU 102). The PDU session establishment accept messagemay include information indicating the MA-PDU session 220 isestablished. At 1240, the NE may receive information indicating that aPDN connection 304 in a second network (e.g., the EPC 306) is to replacethe second access leg of the MA-PDU session 220. At 1250, the NE mayconfigure traffic rules which associate the second access leg of theMA-PDU session 220 with the PDN connection 304. For example, theSMF+PGW-C 318 and the UPF+PGW-U 316 may perform an N4 sessionmodification. For example, the configuring (e.g., reconfiguring) maymodify the traffic forwarding rules (e.g., DL forwarding rules) in theUPF. The traffic that is to be forwarded on the 3GGP access leg may besent on the PDN connection 304. At 1260, the NE may send a PDU sessionmodification message (e.g., to the WTRU 102) and the PDU sessionmodification message may include information indicating an associationof the second access leg of the MA-PDU session 220 with the PDNconnection 304. For example, the information in the PDU SessionModification message may inform the WTRU 102 that data (e.g., uplinkdata) may be sent for the MA-PDU session 220 over the associated PDNconnection 304 in the EPC 306. The WTRU 102 may associate (e.g., locallyassociate) the PDN connection 304 with the MA-DPU session context. Datamay be sent over the PDN connection 304, for example, when the executionof the ATSSS rules points to the 3GGP access.

Although the features and elements of the present disclosure mayconsider New Radio (NR) or 5G specific protocols, it is understood thatthe solutions described herein are not restricted to this scenario andare applicable to other wireless systems as well.

Although features and elements are described above in particularcombinations, one of ordinary skill in the art will appreciate that eachfeature or element can be used alone or in any combination with theother features and elements. In addition, the methods described hereinmay be implemented in a computer program, software, or firmwareincorporated in a computer readable medium for execution by a computeror processor. Examples of non-transitory computer-readable storage mediainclude, but are not limited to, a read only memory (ROM), random accessmemory (RAM), a register, cache memory, semiconductor memory devices,magnetic media such as internal hard disks and removable disks,magneto-optical media, and optical media such as CD-ROM disks, anddigital versatile disks (DVDs). A processor in association with softwaremay be used to implement a radio frequency transceiver for use in a WTRU102, UE, terminal, base station, RNC, or any host computer.

Moreover, in the embodiments described above, processing platforms,computing systems, controllers, and other devices containing processorsare noted. These devices may contain at least one Central ProcessingUnit (“CPU”) and memory. In accordance with the practices of personsskilled in the art of computer programming, reference to acts andsymbolic representations of operations or instructions may be performedby the various CPUs and memories. Such acts and operations orinstructions may be referred to as being “executed,” “computer executed”or “CPU executed.”

One of ordinary skill in the art will appreciate that the acts andsymbolically represented operations or instructions include themanipulation of electrical signals by the CPU. An electrical systemrepresents data bits that can cause a resulting transformation orreduction of the electrical signals and the maintenance of data bits atmemory locations in a memory system to thereby reconfigure or otherwisealter the CPU's operation, as well as other processing of signals. Thememory locations where data bits are maintained are physical locationsthat have particular electrical, magnetic, optical, or organicproperties corresponding to or representative of the data bits. Itshould be understood that the representative embodiments are not limitedto the above-mentioned platforms or CPUs and that other platforms andCPUs may support the provided methods.

The data bits may also be maintained on a computer readable mediumincluding magnetic disks, optical disks, and any other volatile (e.g.,Random Access Memory (“RAM”)) or non-volatile (e.g., Read-Only Memory(“ROM”)) mass storage system readable by the CPU. The computer readablemedium may include cooperating or interconnected computer readablemedium, which exist exclusively on the processing system or aredistributed among multiple interconnected processing systems that may belocal or remote to the processing system. It is understood that therepresentative embodiments are not limited to the above-mentionedmemories and that other platforms and memories may support the describedmethods.

In an illustrative embodiment, any of the operations, processes, etc.described herein may be implemented as computer-readable instructionsstored on a computer-readable medium. The computer-readable instructionsmay be executed by a processor of a mobile unit, a network element,and/or any other computing device.

There is little distinction left between hardware and softwareimplementations of aspects of systems. The use of hardware or softwareis generally (e.g., but not always, in that in certain contexts thechoice between hardware and software may become significant) a designchoice representing cost vs. efficiency tradeoffs. There may be variousvehicles by which processes and/or systems and/or other technologiesdescribed herein may be effected (e.g., hardware, software, and/orfirmware), and the preferred vehicle may vary with the context in whichthe processes and/or systems and/or other technologies are deployed. Forexample, if an implementer determines that speed and accuracy areparamount, the implementer may opt for a mainly hardware and/or firmwarevehicle. If flexibility is paramount, the implementer may opt for amainly software implementation. Alternatively, the implementer may optfor some combination of hardware, software, and/or firmware.

The foregoing detailed description has set forth various embodiments ofthe devices and/or processes via the use of block diagrams, flowcharts,and/or examples. Insofar as such block diagrams, flowcharts, and/orexamples contain one or more functions and/or operations, it will beunderstood by those within the art that each function and/or operationwithin such block diagrams, flowcharts, or examples may be implemented,individually and/or collectively, by a wide range of hardware, software,firmware, or virtually any combination thereof. Suitable processorsinclude, by way of example, a general purpose processor, a specialpurpose processor, a conventional processor, a digital signal processor(DSP), a plurality of microprocessors, one or more microprocessors inassociation with a DSP core, a controller, a microcontroller,Application Specific Integrated Circuits (ASICs), Application SpecificStandard Products (ASSPs); Field Programmable Gate Arrays (FPGAs)circuits, any other type of integrated circuit (IC), and/or a statemachine.

Although features and elements are provided above in particularcombinations, one of ordinary skill in the art will appreciate that eachfeature or element can be used alone or in any combination with theother features and elements. The present disclosure is not to be limitedin terms of the particular embodiments described in this application,which are intended as illustrations of various aspects. Manymodifications and variations may be made without departing from itsspirit and scope, as will be apparent to those skilled in the art. Noelement, act, or instruction used in the description of the presentapplication should be construed as critical or essential to theinvention unless explicitly provided as such. Functionally equivalentmethods and apparatuses within the scope of the disclosure, in additionto those enumerated herein, will be apparent to those skilled in the artfrom the foregoing descriptions. Such modifications and variations areintended to fall within the scope of the appended claims. The presentdisclosure is to be limited only by the terms of the appended claims,along with the full scope of equivalents to which such claims areentitled. It is to be understood that this disclosure is not limited toparticular methods or systems.

It is also to be understood that the terminology used herein is for thepurpose of describing particular embodiments only, and is not intendedto be limiting. As used herein, when referred to herein, the terms“station” and its abbreviation “STA”, “user equipment” and itsabbreviation “UE” may mean (i) a wireless transmit and/or receive unit(WTRU), such as described infra; (ii) any of a number of embodiments ofa WTRU, such as described infra; (iii) a wireless-capable and/orwired-capable (e.g., tetherable) device configured with, inter alia,some or all structures and functionality of a WTRU, such as describedinfra; (iii) a wireless-capable and/or wired-capable device configuredwith less than all structures and functionality of a WTRU, such asdescribed infra; or (iv) the like. Details of an example WTRU, which maybe representative of any UE recited herein, are provided below withrespect to FIGS. 1A-1D.

In certain representative embodiments, several portions of the subjectmatter described herein may be implemented via Application SpecificIntegrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs),digital signal processors (DSPs), and/or other integrated formats.However, those skilled in the art will recognize that some aspects ofthe embodiments disclosed herein, in whole or in part, may beequivalently implemented in integrated circuits, as one or more computerprograms running on one or more computers (e.g., as one or more programsrunning on one or more computer systems), as one or more programsrunning on one or more processors (e.g., as one or more programs runningon one or more microprocessors), as firmware, or as virtually anycombination thereof, and that designing the circuitry and/or writing thecode for the software and or firmware would be well within the skill ofone of skill in the art in light of this disclosure. In addition, thoseskilled in the art will appreciate that the mechanisms of the subjectmatter described herein may be distributed as a program product in avariety of forms, and that an illustrative embodiment of the subjectmatter described herein applies regardless of the particular type ofsignal bearing medium used to actually carry out the distribution.Examples of a signal bearing medium include, but are not limited to, thefollowing: a recordable type medium such as a floppy disk, a hard diskdrive, a CD, a DVD, a digital tape, a computer memory, etc., and atransmission type medium such as a digital and/or an analogcommunication medium (e.g., a fiber optic cable, a waveguide, a wiredcommunications link, a wireless communication link, etc.).

The herein described subject matter sometimes illustrates differentcomponents contained within, or connected with, different othercomponents. It is to be understood that such depicted architectures aremerely examples, and that in fact many other architectures may beimplemented which achieve the same functionality. In a conceptual sense,any arrangement of components to achieve the same functionality iseffectively “associated” such that the desired functionality may beachieved. Hence, any two components herein combined to achieve aparticular functionality may be seen as “associated with” each othersuch that the desired functionality is achieved, irrespective ofarchitectures or intermediate components. Likewise, any two componentsso associated may also be viewed as being “operably connected”, or“operably coupled”, to each other to achieve the desired functionality,and any two components capable of being so associated may also be viewedas being “operably couplable” to each other to achieve the desiredfunctionality. Specific examples of operably couplable include but arenot limited to physically mateable and/or physically interactingcomponents and/or wirelessly interactable and/or wirelessly interactingcomponents and/or logically interacting and/or logically interactablecomponents.

With respect to the use of substantially any plural and/or singularterms herein, those having skill in the art can translate from theplural to the singular and/or from the singular to the plural as isappropriate to the context and/or application. The varioussingular/plural permutations may be expressly set forth herein for sakeof clarity.

It will be understood by those within the art that, in general, termsused herein, and especially in the appended claims (e.g., bodies of theappended claims) are generally intended as “open” terms (e.g., the term“including” should be interpreted as “including but not limited to,” theterm “having” should be interpreted as “having at least,” the term“includes” should be interpreted as “includes but is not limited to,”etc.). It will be further understood by those within the art that if aspecific number of an introduced claim recitation is intended, such anintent will be explicitly recited in the claim, and in the absence ofsuch recitation no such intent is present. For example, where only oneitem is intended, the term “single” or similar language may be used. Asan aid to understanding, the following appended claims and/or thedescriptions herein may contain usage of the introductory phrases “atleast one” and “one or more” to introduce claim recitations. However,the use of such phrases should not be construed to imply that theintroduction of a claim recitation by the indefinite articles “a” or“an” limits any particular claim containing such introduced claimrecitation to embodiments containing only one such recitation, even whenthe same claim includes the introductory phrases “one or more” or “atleast one” and indefinite articles such as “a” or “an” (e.g., “a” and/or“an” should be interpreted to mean “at least one” or “one or more”). Thesame holds true for the use of definite articles used to introduce claimrecitations. In addition, even if a specific number of an introducedclaim recitation is explicitly recited, those skilled in the art willrecognize that such recitation should be interpreted to mean at leastthe recited number (e.g., the bare recitation of “two recitations,”without other modifiers, means at least two recitations, or two or morerecitations).

Furthermore, in those instances where a convention analogous to “atleast one of A, B, and C, etc.” is used, in general such a constructionis intended in the sense one having skill in the art would understandthe convention (e.g., “a system having at least one of A, B, and C”would include but not be limited to systems that have A alone, B alone,C alone, A and B together, A and C together, B and C together, and/or A,B, and C together, etc.). In those instances where a conventionanalogous to “at least one of A, B, or C, etc.” is used, in general sucha construction is intended in the sense one having skill in the artwould understand the convention (e.g., “a system having at least one ofA, B, or C” would include but not be limited to systems that have Aalone, B alone, C alone, A and B together, A and C together, B and Ctogether, and/or A, B, and C together, etc.). It will be furtherunderstood by those within the art that virtually any disjunctive wordand/or phrase presenting two or more alternative terms, whether in thedescription, claims, or drawings, should be understood to contemplatethe possibilities of including one of the terms, either of the terms, orboth terms. For example, the phrase “A or B” will be understood toinclude the possibilities of “A” or “B” or “A and B.” Further, the terms“any of” followed by a listing of a plurality of items and/or aplurality of categories of items, as used herein, are intended toinclude “any of,” “any combination of,” “any multiple of,” and/or “anycombination of multiples of” the items and/or the categories of items,individually or in conjunction with other items and/or other categoriesof items. Moreover, as used herein, the term “set” or “group” isintended to include any number of items, including zero. Additionally,as used herein, the term “number” is intended to include any number,including zero.

In addition, where features or aspects of the disclosure are describedin terms of Markush groups, those skilled in the art will recognize thatthe disclosure is also thereby described in terms of any individualmember or subgroup of members of the Markush group.

As will be understood by one skilled in the art, for any and allpurposes, such as in terms of providing a written description, allranges disclosed herein also encompass any and all possible subrangesand combinations of subranges thereof. Any listed range can be easilyrecognized as sufficiently describing and enabling the same range beingbroken down into at least equal halves, thirds, quarters, fifths,tenths, etc. As a non-limiting example, each range discussed herein maybe readily broken down into a lower third, middle third and upper third,etc. As will also be understood by one skilled in the art all languagesuch as “up to,” “at least,” “greater than,” “less than,” and the likeincludes the number recited and refers to ranges which can besubsequently broken down into subranges as discussed above. Finally, aswill be understood by one skilled in the art, a range includes eachindividual member. Thus, for example, a group having 1-3 cells refers togroups having 1, 2, or 3 cells. Similarly, a group having 1-5 cellsrefers to groups having 1, 2, 3, 4, or 5 cells, and so forth.

Moreover, the claims should not be read as limited to the provided orderor elements unless stated to that effect. In addition, use of the terms“means for” in any claim is intended to invoke 35 U.S.C. §112, ¶ 6 ormeans-plus-function claim format, and any claim without the terms “meansfor” is not so intended.

A processor in association with software may be used to implement aradio frequency transceiver for use in a wireless transmit receive unit(WTRU), user equipment (UE), terminal, base station, Mobility ManagementEntity (MME) or Evolved Packet Core (EPC), or any host computer. TheWTRU may be used m conjunction with modules, implemented in hardwareand/or software including a Software Defined Radio (SDR), and othercomponents such as a camera, a video camera module, a videophone, aspeakerphone, a vibration device, a speaker, a microphone, a televisiontransceiver, a hands free headset, a keyboard, a Bluetooth® module, afrequency modulated (FM) radio unit, a Near Field Communication (NFC)Module, a liquid crystal display (LCD) display unit, an organiclight-emitting diode (OLED) display unit, a digital music player, amedia player, a video game player module, an Internet browser, and/orany Wireless Local Area Network (WLAN) or Ultra Wide Band (UWB) module.

Although the invention has been described in terms of communicationsystems, it is contemplated that the systems may be implemented insoftware on microprocessors/general purpose computers (not shown). Incertain embodiments, one or more of the functions of the variouscomponents may be implemented in software that controls ageneral-purpose computer.

In addition, although the invention is illustrated and described hereinwith reference to specific embodiments, the invention is not intended tobe limited to the details shown. Rather, various modifications may bemade in the details within the scope and range of equivalents of theclaims and without departing from the invention.

Throughout the disclosure, one of skill understands that certainrepresentative embodiments may be used in the alternative or incombination with other representative embodiments.

Although features and elements are described above in particularcombinations, one of ordinary skill in the art will appreciate that eachfeature or element can be used alone or in any combination with theother features and elements. In addition, the methods described hereinmay be implemented in a computer program, software, or firmwareincorporated in a computer readable medium for execution by a computeror processor. Examples of non-transitory computer-readable storage mediainclude, but are not limited to, a read only memory (ROM), random accessmemory (RAM), a register, cache memory, semiconductor memory devices,magnetic media such as internal hard disks and removable disks,magneto-optical media, and optical media such as CD-ROM disks, anddigital versatile disks (DVDs). A processor in association with softwaremay be used to implement a radio frequency transceiver for use in aWRTU, UE, terminal, base station, RNC, or any host computer.

Moreover, in the embodiments described above, processing platforms,computing systems, controllers, and other devices containing processorsare noted. These devices may contain at least one Central ProcessingUnit (“CPU”) and memory. In accordance with the practices of personsskilled in the art of computer programming, reference to acts andsymbolic representations of operations or instructions may be performedby the various CPUs and memories. Such acts and operations orinstructions may be referred to as being “executed,” “computer executed”or “CPU executed.”

One of ordinary skill in the art will appreciate that the acts andsymbolically represented operations or instructions include themanipulation of electrical signals by the CPU. An electrical systemrepresents data bits that can cause a resulting transformation orreduction of the electrical signals and the maintenance of data bits atmemory locations in a memory system to thereby reconfigure or otherwisealter the CPU's operation, as well as other processing of signals. Thememory locations where data bits are maintained are physical locationsthat have particular electrical, magnetic, optical, or organicproperties corresponding to or representative of the data bits.

The data bits may also be maintained on a computer readable mediumincluding magnetic disks, optical disks, and any other volatile (e.g.,Random Access Memory (“RAM”)) or non-volatile (“e.g., Read-Only Memory(“ROM”)) mass storage system readable by the CPU. The computer readablemedium may include cooperating or interconnected computer readablemedium, which exist exclusively on the processing system or aredistributed among multiple interconnected processing systems that may belocal or remote to the processing system. It is understood that therepresentative embodiments are not limited to the above-mentionedmemories and that other platforms and memories may support the describedmethods.

Suitable processors include, by way of example, a general purposeprocessor, a special purpose processor, a conventional processor, adigital signal processor (DSP), a plurality of microprocessors, one ormore microprocessors in association with a DSP core, a controller, amicrocontroller, Application Specific Integrated Circuits (ASICs),Application Specific Standard Products (ASSPs); Field Programmable GateArrays (FPGAs) circuits, any other type of integrated circuit (IC),and/or a state machine.

Although the invention has been described in terms of communicationsystems, it is contemplated that the systems may be implemented insoftware on microprocessors/general purpose computers (not shown). Incertain embodiments, one or more of the functions of the variouscomponents may be implemented in software that controls ageneral-purpose computer.

In addition, although the invention is illustrated and described hereinwith reference to specific embodiments, the invention is not intended tobe limited to the details shown. Rather, various modifications may bemade in the details within the scope and range of equivalents of theclaims and without departing from the invention.

Claims: 1.-31. (canceled)
 32. A method implemented by a wirelesstransmit/receive unit (WTRU) to manage a multi-access protocol data unit(MA-PDU) session, including a first access leg in a first network and asecond access leg in the first network, the method comprising: sending,by the WTRU, information indicating (1) a request to establish a packetdata network (PDN) connection in a second network and (2) the PDNconnection is to replace the second access leg of the MA-PDU session;receiving, by the WTRU, information indicating an association of thesecond access leg of the MA-PDU session with the PDN connection; andcommunicating, by the WTRU, data for the MA-PDU session via (1) via thefirst access leg in the first network and (2) the PDN connection in thesecond network.
 33. The method of claim 32, wherein the first access legis a non-third generation partnership project (non-3GPP) access legusing a first radio access technology to communicate with the firstnetwork and the second access leg is a third generation partnershipproject (3GGP) access leg using a second radio access technology tocommunicate with the first network.
 34. The method of claim 32, whereinthe first network is a 5G core (5GC) network, and the second network isan evolved packet core (EPC) network.
 35. The method of claim 32,further comprising: establishing the MA-PDU session prior to the sendingof the information indicating (1) the request to establish the PDNconnection in the second network and (2) the PDN connection is toreplace the second access leg of the MA-PDU session.
 36. The method ofclaim 32, further comprising: sending, by the WTRU, a PDN connectivityrequest to the second network to establish the PDN connection, whereinthe PDN connectivity request includes the information indicating (1) therequest to establish the PDN connection in the second network and (2)the PDN connection is to replace the second access leg of the MA-PDUsession.
 37. The method of claim 32, wherein the information indicates(1) the request to establish the PDN connection in the second networkand (2) the PDN connection is to replace the second access leg of theMA-PDU session, and (3) an identifier of the MA-PDU session.
 38. Themethod of claim 32, wherein the communicating, by the WTRU, the data forthe MA-PDU session via (1) via the first access leg in the first networkand (2) the PDN connection in the second network includes: sending, bythe WTRU, uplink data for the MA-PDU session via the PDN connection inthe second network.
 39. The method of claim 38, further comprising:determining, by the WTRU, the data for the MA-PDU session is to be sentvia the PDN connection based on one or more configured rules.
 40. Themethod of claim 32, wherein the one or more configured rules include anyof at least one access traffic steering, switching and splitting (ATSSS)rule and/or at least one quality of service (QoS) rule.
 41. The methodof claim 32, wherein the communicating, by the WTRU, the data for theMA-PDU session via (1) via the first access leg in the first network and(2) the PDN connection in the second network includes: receiving, by theWTRU, downlink data for the MA-PDU session via the PDN connection in thesecond network.
 42. A wireless transmit/receive unit (WTRU) which isconfigured to manage a multi-access protocol data unit (MA-PDU) sessionincluding a first access leg in a first network and a second access legin the first network, the WTRU comprising: a processor and transceiverwhich are configured to: send information indicating (1) a request toestablish a packet data network (PDN) connection in a second network and(2) the PDN connection in the second network is to replace the secondaccess leg of the MA-PDU session, receive information indicating anassociation of the second access leg of the MA-PDU session with the PDNconnection, and communicate data for the MA-PDU session via (1) thefirst access leg in the first network and (2) the PDN connection in thesecond network.
 43. The WTRU of claim 42, wherein the first access legis a non-third generation partnership project (non-3GPP) access legusing a first radio access technology to communicate with the firstnetwork and the second access leg is a third generation partnershipproject (3GGP) access leg using a second radio access technology tocommunicate with the first network.
 44. The WTRU of claim 42, whereinthe first network is a 5G core (5GC) network, and the second network isan evolved packet core (EPC) network.
 45. The WTRU of claim 42, whereinthe processor and the transceiver are configured to: establish theMA-PDU session prior to the sending of the information indicating (1)the request to establish the PDN connection in the second network and(2) the PDN connection is to replace the second access leg of the MA-PDUsession.
 46. The WTRU of claim 42, wherein the processor and thetransceiver are configured to: send, by the WTRU, a PDN connectivityrequest to the second network to establish the PDN connection, whereinthe PDN connectivity request includes the information indicating (1) therequest to establish the PDN connection in the second network and (2)the PDN connection is to replace the second access leg of the MA-PDUsession.
 47. The WTRU of claim 42, wherein the information indicates (1)the request to establish the PDN connection in the second network and(2) the PDN connection is to replace the second access leg of the MA-PDUsession, and (3) an identifier of the MA-PDU session.
 48. The WTRU ofclaim 42, wherein the processor and the transceiver are configured to:communicate, by the WTRU, the data for the MA-PDU session via (1) viathe first access leg in the first network and (2) the PDN connection inthe second network including to: send, by the WTRU, uplink data for theMA-PDU session via the PDN connection in the second network.
 49. TheWTRU of claim 42, wherein the processor and the transceiver areconfigured to: determine, by the WTRU, the data for the MA-PDU sessionis to be sent via the PDN connection based on one or more configuredrules.
 50. The WTRU of claim 49, wherein the one or more configuredrules include any of at least one access traffic steering, switching andsplitting (ATSSS) rule and/or at least one quality of service (QoS)rule.
 51. The WTRU of claim 42, wherein the processor and thetransceiver are further configured to: communicate, by the WTRU, thedata for the MA-PDU session via (1) via the first access leg in thefirst network and (2) the PDN connection in the second network includingto: receive, by the WTRU, downlink data for the MA-PDU session via thePDN connection in the second network.